Radio Button

I am trying to use the standard Modern UI installer.

I have 2 radio buttons, neither is checked by default

I want the Next button to be greyed out unless one of the radio buttons is checked

What is the best way to do this?

I only know how to do this with nsDialogs. It might perhaps also be possible with InstallOptions, but I would not know how.

1) Grey out the Next button before you call nsDialogs::Show
2) Define an OnClick callback function for both radio buttons using ${NSD_OnClick}
3) In those callback functions, enable the Next button.

Does anybody have any example code where this has been done?

NSIS\Docs\nsDialogs\Readme.html
NSIS\Examples\nsDialogs\example.nsi

Thanks. I will take a look